This invention relates generally to receptacles for material handling, and more particularly to flexible, collapsible receptacles for use in the storage, transportation and dispensation of flowable materials in semi-bulk quantities.
Traditionally, the handling of flowable materials and specifically dry particulate or granular materials have presented unique problems. For instance, these materials include chemicals, minerals, fertilizers, foodstuffs, grains, agricultural products and the like. Generally, such materials have been handled chiefly by two types of material handling systems. Where large quantities of material are required, specialized bulk handling equipment is used. For example, materials are loaded into a truck, railroad car or barge at the supply location and then transported to a place of unloading where the materials are transferred to a hopper or other storage device. The materials are distributed from this point to the actual destination sites. Although such bulk material handling systems can efficiently transport such materials, they are limited in flexibility. The material must be handled in large quantities and the transfer can occur only in those places convenient to these transportation systems. In addition, sanitary standards are more difficult to maintain. Since the materials are often exposed during at least part of the handling, there is always the possibility of damage or contamination. Consequently, the characteristics of the particular material involved also affect the flexibility of a bulk handling system.
Where smaller quantities of material are required, a container system is used. These packages may take the form of drums, bags, boxes, baskets or other types of individual packages. Consider the cement industry, for example. Cement, mortar and the like are loaded in paper sacks capable of containing 50 to 100 lbs. of material. The sacks are separately filled, loaded on vehicles, transported to a point of distribution, unloaded and stored in this form. At the work site, the bags are individually opened, emptied and then discarded. Despite some conveniences in using the container system, there are attendant disadvantages. The handling costs are higher because the packages must be loaded, unloaded, and emptied individually. Since numerous containers are often required, higher costs are also incurred on the basis of units of material shipped per container, and particularly if the container can be utilized but once. On the other hand, reusable packages are relatively more expensive and are frequently of rigid or noncollapsible construction whereby return freight costs can be substantial. Finally, losses from breakage, moisture or other contamination can be considerable where the containers are constructed of a porous material, such as cotton or paper.
In addition, various problems frequently arise relative to discharging the material contents from the container. Depending upon the material, interruption of the container unloading operation can result when the discharge means becomes clogged. This frequently occurs when shipping moist or compactable materials which tend to cake, or bridge across the discharge opening. This problem can be alleviated by using a larger discharge opening; however, a large discharge opening often results in a loss of control of the material discharge. Consequently, a small discharge opening allows greater control, but often requires the time consuming and therefore costly step of clearing blockages.
The present invention comprises a material receptacle which overcomes the foregoing and other problems long since associated with the prior art. The present invention utilizes a new and improved flexible receptacle for handling materials in semi-bulk quantities which incorporates the convenience of a package container system with the economy of the bulk shipping system. In accordance with the broader aspects of the invention, an improved flexible receptacle comprises a unique sling and woven container arrangement. The container features top loading and bottom discharge. The receptacle can be used with virtually any flowable material, such as minerals, chemicals fertilizers, foodstuffs, and agricultural products. The receptacle of the present invention can be easily transported or handled by one individual with appropriate equipment even though the weight capacity can be as high as 3,000 lbs. or more. Pallets are not necessary, thereby reducing the tare weight and increasing the shipping efficiency. Because the receptacle is constructed from a durable, laminate material, it can be transported or stored in an exposed condition without damage to the contents. The receptacles can be stacked for high density storage or transportation, which further increases shipping efficiency. The top loading and bottom discharge features of the receptacle provide advantages to both the vendor and the user of the contents. Gravity fill and discharge are facilitated. The receptacle can be used as a dispenser and functions as a hopper when supported. Finally, the flexible receptacle comprising the invention is completely collapsible and can be reused if desired.
In accordance with more specific aspects of the invention, a semi-bulk receptacle for flowable materials comprises a woven container supported by a sling assembly. The container includes a bottom portion and an upstanding side portion. The side portion is formed from one or more panels sewn together at the vertical edges. The lower edge of the cylindrical side portion is sewn to the periphery of the bottom portion, which includes a discharge spout and closure therefor. The side and bottom portions of the container are preferably formed of a unique laminate material which consists of an outer layer of woven polypropylene adhesively secured to an inner layer of polybutylene film. The woven polypropylene affords great strength and durability, while the polybutylene film serves as a flexible moisture barrier whereby the contents of the receptacle are protected from damage during handling and transit. Other woven materials with sufficient strength can be used, if desired, to construct the container. The sling assembly, which is preferably constructed of polyester webbing, supports the collapsible container. The sling comprises lift straps attached to a bottom ring. Specifically, four lift straps are secured to the bottom ring at equal intervals. With the ring surrounding the discharge spout, part of the support sling is sewn to the bottom portion of the container. The sling assembly is also sewn through the lift straps to the side portion of the container. Each lift strap is folded over the adjacent container side portion and sewn continuously along the vertical distance between the bottom and the fill height of the container. As a result, the stress is more evenly distributed between the support sling and the durable container material. In addition, supporting the receptacle by the sling aids discharge; by tending to squeeze the container, the sling reduces material bridging across the discharge spout. To allow top loading of the receptacle, the top of the container can be gathered and closed with a removable wire tie, or provided with a spout similar to the discharge spout.
In another embodiment of the invention, the container comprises only an upstanding side portion formed from one or more panels of woven material sewn together at the edges. The ends of the container are gathered and closed with wire ties. The sling assembly comprises four lift straps sewn to the container. Each lift strap includes a lift loop at the upper end and a guide loop at the lower end. A draw rope passing through the guide loops surrounds the bottom wire tie and supports the bottom of the container. Release of the lower wire tie and draw rope permits full open discharge of the container without interruption due to material bridging or clogging.